>> PAGE_OFFSET is 0x78000000 with VMSPLIT_2G, this address is in the middle>> of the second pgd entry with pae enabled. This breaks assumptions>> (address is aligned to pgd entry's address) in a lot of places like>> pagetable_init. Fixing the assumptions is hard (eg, low mapping). SO I>> just changed the address to 0x80000000.>>Do we allow user entering arbitrary value here? In any case, it would>be nice to document alignment requirements of this one, because>otherwise someone *will* get it wrong.

There was a reason 0x78000000 was chosenhttp://marc.theaimsgroup.com/?l=linux-kernel&m=113690073801820&w=2

Though further back in http://marc.theaimsgroup.com/?l=linux-kernel&m=113689790817521&w=20x80000000 was indeed posted.